Integrated circuit inductor with a magnetic core
View Patent ↗An inductor is fabricated on a substrate having a top surface and a bottom surface. The inductor includes a plurality of holes extending through the substrate, wherein the plurality of holes interconnect the top surface and the bottom surface of the substrate. The inductor also includes a plurality of conductive posts formed in the plurality of holes and a plurality of conductive segments formed on the top surface and on the bottom surface that interconnect the conductive posts such that a continuous conductive coil is formed. The inductor also includes a magnetic core that occupies substantially the entire volume enclosed by the conductive coil.
1. A method of fabricating an inductor comprising:
forming a plurality of vias in a substrate;
forming a magnetic core within the substrate;
depositing a first metallic material into the vias to form a plurality of metallic posts; and
fabricating a plurality of conductive segments that interconnect the plurality of metallic posts to form a conductive coil surrounding the magnetic core.
2. The method of claim 1 , wherein forming the plurality of vias comprises extending the vias entirely through the substrate.
3. The method of claim 1 , wherein forming the plurality of vias comprises forming two substantially parallel rows of vias extending through the substrate.
4. The method of claim 1 , wherein forming the plurality of vias comprises using an etching process.
5. The method of claim 1 , wherein forming the plurality of vias comprises using a laser.
6. The method of claim 1 , wherein the substrate comprises a semiconductor wafer.
7. The method of claim 1 , wherein the substrate comprises silicon.
8. The method of claim 1 , wherein the substrate comprises silicon carbide.
9. The method of claim 1 , wherein the substrate comprises germanium.
10. The method of claim 1 , wherein forming the magnetic core comprises depositing a magnetic oxide.
11. The method of claim 1 , wherein forming the magnetic core comprises depositing ferromagnetic material by chemical vapor deposition.
12. The method of claim 1 , wherein forming a magnetic core comprises:
forming a porous region in the substrate; and
depositing a ferromagnetic material in the porous region.
13. The method of claim 1 , wherein forming the conductive coil comprises depositing copper.
14. The method of claim 1 , wherein forming the conductive coil comprises depositing gold.
15. The method of claim 1 , wherein fabricating the plurality of conductive segments comprises forming a plurality of conductive straps interconnecting the metallic posts to form the conductive coil.
16. The method of claim 15 , wherein forming the plurality of conductive straps comprises using a second metallic material, wherein the first metallic material is not the same as the second metallic material.
17. The method of claim 15 , wherein the metallic posts are configured in two substantially parallel rows.
18. The method of claim 1 , wherein the substrate has at least two substantially parallel surfaces, and wherein the metallic posts are substantially perpendicular to the parallel surfaces.
19. The method of claim 1 , wherein the metallic posts have circular cross-sections.
20. The method of claim 1 , wherein the metallic posts are at least partially surrounded by an insulating material.
21. The method of claim 20 , wherein the insulating material comprises polyimide.
22. The method of claim 1 , wherein the inductor has an inductance of at least 1 nanohenry.
23. The method of claim 1 , further comprising covering the conductive coil with a passivation layer.
24. The method of claim 23 , wherein the passivation layer is configured to electrically insulate the inductor and to protect the inductor from physical damage.
25. The method of claim 1 , further comprising operatively coupling the inductor to an integrated circuit formed on the substrate.
26. The method of claim 25 , wherein the integrated circuit is a computer memory circuit.
27. An inductor comprising:
a substrate;
a magnetic core formed within the substrate;
a plurality of vias filled with a metallic material providing a plurality of metallic posts through the substrate; and
a plurality of conductive segments interconnecting the plurality of conductive posts to form a conductive coil surrounding the magnetic core.
28. The inductor of claim 27 , wherein the substrate comprises a semiconductor wafer.
29. The inductor of claim 27 , wherein the substrate comprises silicon.
30. The inductor of claim 27 , wherein the magnetic core comprises a porous region of the substrate treated with a ferromagnetic material.
31. The inductor of claim 27 , wherein the metallic material in the vias comprises copper.